The Role of Behavioral Interventions in Reducing Residential Water Usage: Case Study from Cape Town, South Africa

This study on the role of behavioral interventions in promoting water conservation is to be rolled-out to residential consumers in the City of Cape Town, South Africa. Our unit of randomization is the household and our outcome variable is household water consumption (liters per month). Participating households have been allocated into nine treatment groups (which receive the interventions or behavioral messages) and a control group (which receives no intervention). The nine behavioral messages are to be sent via billing inserts with the monthly municipal water bills.
The interventions can be described in terms of:
A. Information Provision - Increasing salience
B. Financial Gains & Loss Framings
C. Social Norm Framing
D. Pro-social Framings
E. Social Recognition Framings

Our intervention is focused around a series of behavioral messages or nudges that aims to incentivize households to conserve water. Each of the treatments are described below:

Treatment 1: Tips
Provision of water conservation tips to the household in a one-page bill-insert. Each tip is presented using a descriptive icon, a short sentence and a paragraph explaining potential water savings (liters per month for an average family of four) when the tip is followed. Tips are presented in two groups: 1) quick fixes (take short showers, don't leave taps running, have a smaller bath, fix leaks immediately, practice water-wise-gardening) and 2) smart purchases (use a water-saving showerhead, fit taps with water-saving devices, reduce the water used per flush, use pool of cover).
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The remaining eight treatments use the conservation tips introduced in treatment 1 as support material. The conservation tips are placed on the back of the page wherein the main treatment is introduced.
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Treatment 2: Water Consumption Graph
This bill-insert (treatment) presents a breakdown of the household's monthly water bill according to the City of Cape Town's block tariff scheme. The breakdown is presented in a graph (Water Consumption Graph) showing that as water consumption increases, the tariff (in rand per litter) increases in a stepwise manner. The Water Consumption Graph makes salient how much water the household has consumed under the different tariffs and how the total bill (in rand) was calculated.

Treatment 3: Financial Gains
This treatment frames efficient water usage as a financial gain. A descriptive text explains how much money would have the household saved, had its water consumption fallen in a lower tariff block. The descriptive text is presented along the Water Consumption Graph as introduced in treatment 2.

Treatment 4: Financial Loss
This treatment frames inefficient water usage as a financial loss. A descriptive text explains how much money the household has lost by not having consumed in a lower tariff block. The descriptive text is presented along the Water Consumption Graph as introduced in treatment 2.

Treatment 5: Social Norm
This treatment frames the household's water consumption (in litters) in relation to that of the average consumption of its neighbors. This comparison is presented in both a descriptive text and a bar graph.

Treatment 6: Public Good
This treatment encourages households to voluntary reduce their water consumption in order to reduce the stress on water resources and prevent future water restrictions. It emphasizes that a water-scarce city needs every household to save water.

Treatment 7: Intrinsic Motivation
This treatment asks households to voluntary reduce their water consumption by 10% in order to support a water saving initiative that was recently launched by the City.

Treatment 8: Social Recognition
This treatment encourages households to reduce their water consumption by 10% in order to support a water saving initiative that was recently launched by the City. The heads of those households that achieve this goal in a six month period will be publicly announced in the City's webpage.

Treatment 9: Social Recognition with Opt-Out Option
This treatment is the same as treatment 9 except from the fact that it allows households to opt out from having their names published on the City's website.

2015-11-06

2016-05-31

Reduction in Daily Average Water Consumption
Increased Water Savings
Reduced Expenditure on Water per Household
Improved consciousness around water use

Participating households have been allocated into nine treatment groups (which receive the interventions or behavioral messages) and a control group (which receives no intervention). The nine behavioral messages are to be sent via billing inserts with the monthly municipal water bills. Each household will receive a monthly insert in their bill for 6 consecutive months.

Randomization done in office by a computer

Household level Randomization

No

No clustering

413 000 X 6months

Note: our sample comprise both indigent and non-indigent households.

Control total: 48,207
T1 total: 49,928
T2 total: 34,000
T3 total: 33,688
T4 total: 34,073
T5 total: 40,001
T6 total: 40,058
T7 total: 44,174
T8 total: 43,930
T9 total: 44,421